Interdisciplinary studies of North Atlantic and Labrador Sea margin architecture and sedimentary processes, preliminary results of investigations during the TTR-3 cruise of RV Professor Logachev, July-September, 2003
Kenyon, N. H.; Ivanov, M.K.; Akhmetzhanov, A. M.; Kozlova, E.V.; Mazzini, A. (2004). Interdisciplinary studies of North Atlantic and Labrador Sea margin architecture and sedimentary processes, preliminary results of investigations during the TTR-3 cruise of RV Professor Logachev, July-September, 2003. Technical Series. Intergovernmental Oceanographic Commission = Série technique, 68. UNESCO: Paris. 92, II annexes pp.
Part of: IOC Technical Series. Intergovernmental Oceanographic Commission = Série technique. UNESCO: Paris. ISSN 0074-1175
Interdisciplinary studies of North Atlantic and Labrador Sea margin architecture and sedimentary processes were conducted by RV Professor Logachev during the 13th Cruise of the UNESCO-IOC Training-Trough-Research Programme. The studies were carried out in 8 areas. Four locations were visited on the Norwegian margin. Areas 1 and 2 are situated on the Voring Plateau compressing two fields of shallow diapiric structures of similar nature to diapirs of the Vema filed studied during TTR-8 cruise in 1998. As a continuation of this work, seismic and acoustic stiudies of the Vigrid (Area1) and Vivian (Area 2) diapir fields, located on the Voring Marginal High and the Voring Basin respectively, were undertaken.Studies in the Area 3 focussed on the Traenadjupet Slide and Lofoten bassin floor. The distal part of the slide wasstudied in detail with the help of sidescan sonar, high resolution seismic profiles and bottom sampling in order to elucidate the processes and age of sediment failure.The Lofoten Basin Channel was crossed on the lower slope where it has a thick unit of acoustically laminated sediments on its northern flank. A deep towed sidescan sonar line across the distal part of the channel shows erosional features on the channel floor especially where it cuts through a probable slide deposit. The area beyond the channel, which had been proved to be difficult to sample on this and an earlier cruise, was succesfully sampled by the vibracorer and found to be sandy. A highlight of this study was discovery of possible sand volcanoes on the channel-mouth lobe.In the 4th area comprising Andoya Slide and Andoya Canyon a large dataset was obtained using high-resolution sidescan sonar, onboard profiler and coring. It will help to identify the age of the most recent slide event and to study sediments that overlie the slide deposits. The adjacent Andoya Canyon was investigated with Sidescan sonar, TV-system and bottom sampling in order to confirm the types of processes transporting sediments through the canyon and whether they are still active.On the passage to Reykjavik (Iceland) a seismic/hull mounted profiler line was run across several supposed diapiric structures on the floor of the Norwegian Basin (Area 5) between the Aegir and Jan Mayen Ridges. The presence of diapiric structures was confirmed.On the Greenland margin studies were conducted in two main areas. In Area 6 the Eirik Ridge, whose sedimentary sequence represents an excellent record of the history of global ocean circulation and climate change, was investigated. Location of sites with the highest deposition rate during the Holocene was main goal of the investigations. A deep towed profile was used to get a high resolution acoustic record and two cores were obtained for detailed analysis, and in particular to determine whether there is evidence for high frequency changes of current speed. This was a reconnaissance for a further UK research cruise to the area in 2004 that will obtain more cores and undertake current measurements.Principal targets of investigation with Area 7 covering the northern margin of the Labrador Sea and Davis Strait were chosen on the basis of multi-channel seismic data of the Geological Survey of Denmark and Greenland. Positive ("diapir-like") structures on the sea bottom were studied in detail with a variety of methods. Samples collected from two of these structures suggest a volcanic and crystalline basement rather than a diapiric origin.The Pre-Neogene seabed outcrops were studied on the flanks of canyons and valleys extending from the upper continental slope into the deep-water basin west of the Fylla Bank and the Davis Strait High area. Lithology of the samples and biological specimens were preliminarily identified onboard and stored for shipment ashore and further analysis.The areas studied for possible gas or fluid seeping were proved to be strongly disturbed by iceberg ploughing, which provided an unexpected opportunity for studies of the glacial history of the Davs Strait area. Along with a series of gravity cores from the seep areas a unique sandy-gravelly core was collected with a vibracorer in the northernmost of the study areas.Area 8 located along the western Porcupine Bank on the Irish margin contained a large field of giant carbonate mounds. Recent depositional environments and processes were investigated in detail with a suite of high-resolution equipment. An extensive collection of seabed samples, including carbonate crusts of different types, was obtained. The study highlights the relationship between the mounds and the underlying basement structure.
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